Express each of the following odd numbers are the sum of 3 prime numbers

15:

Step 1: Identify three prime numbers that add up to 15.
$3 + 5 + 7 = 15$
Verify: 3 is prime, 5 is prime, 7 is prime.

$\mathbf{15 = 3 + 5 + 7}$

21:

Step 1: Identify three prime numbers that add up to 21.
$7 + 7 + 7 = 21$
Verify: 7 is prime (used three times).

$\mathbf{21 = 7 + 7 + 7}$

27:

Step 1: Identify three prime numbers that add up to 27.
$3 + 7 + 17 = 27$
Verify: 3 is prime, 7 is prime, 17 is prime.
$3 + 7 = 10$
$10 + 17 = 27$

$\mathbf{27 = 3 + 7 + 17}$

33:

Step 1: Identify three prime numbers that add up to 33.
$11 + 11 + 11 = 33$
Verify: 11 is prime (used three times).

$\mathbf{33 = 11 + 11 + 11}$